1. Field of the Invention
The present invention relates to the field of marine radar for collision avoidance and navigation at sea, for locating navigation waypoints and hazards, for assessing wave conditions, and for monitoring ship traffic from a shore-based location. Related applications include surveillance of borders, harbors, coastlines, and secure facilities. An extension of the basic design provides surveillance of the airspace.
2. Prior Art
Marine radars commonly employ large mechanically rotating antennas to provide accurate bearing measurements, and also high-power magnetron transmitters to provide high detection sensitivity. As a result, such radars are expensive to operate and maintain.
Some radars designed for other applications employ array antennas that can be electronically steered, avoiding the mechanical rotation mechanism. The modern version of the array antenna has independent transmit and receive capability at each array element. This antenna technology is often called active electronic scanned array (AESA). These arrays are usually constructed on a planar surface.
Monopulse processing commonly refers to the way the antenna is configured to provide multiple receive channels for the measurement of angle. It encompasses both pulsed and continuous frequency modulated waveforms, as well as multiple waveform repetition intervals that are coherently processed to obtain Doppler resolution.